Classifications

• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D11/00—Inks
  • C09D11/02—Printing inks
  • C09D11/10—Printing inks based on artificial resins
  • C09D11/101—Inks specially adapted for printing processes involving curing by wave energy or particle radiation, e.g. with UV-curing following the printing

Definitions

• This invention concerns inks for use in ink-jet printers.
• this invention concerns inks for use in ink-jet printers that are cured using ultraviolet radiation.
• ink-jet printing minute droplets of black or coloured ink are ejected in a controlled manner from one or more reservoirs or printing heads through narrow nozzles on to a substrate which is moving relative to the reservoirs.
• the ejected ink forms an image on the substrate.
• the inks must flow rapidly from the printing heads, and, to ensure that this happens, they must have in use a low viscosity, typically below 50 mPas at 25°C although in most applications the viscosity should be below 25 mPas.
• the ink when ejected through the nozzles, the ink has a viscosity of 10.5 mPas at the jetting temperature which is usually elevated to about 40°C (the ink might have a much higher viscosity at ambient temperature).
• the inks must also be resistant to drying or crusting in the reservoirs or nozzles.
• ink- jet inks for application at or near ambient temperatures are commonly formulated to contain a large proportion of a mobile liquid vehicle or solvent. In one common type of ink-jet ink this liquid is water - see for example the paper by Henry R. Kang in the Journal of Imaging Science, 35(3), pp. 179-188 (1991).
• the liquid is a low-boiling solvent or mixture of solvents - see, for example, EP 0 314 403, EP 0 424 714 and GB9927247.8.
• ink-jet inks that include a large proportion of water or solvent cannot be handled after printing until the inks have dried, either by evaporation of the solvent or its absorption into the substrate. This drying process is often slow and in many cases (for example, when printing on to a heat-sensitive substrate such as paper) cannot be accelerated.
• ink-jet ink contains unsaturated organic compounds, termed monomers, which polymerise by irradiation, commonly with ultraviolet light, in the presence of a photoinitiator.
• monomers which polymerise by irradiation, commonly with ultraviolet light, in the presence of a photoinitiator.
• This type of ink has the advantage that it is not necessary to evaporate the liquid phase to dry the print; instead the print is exposed to radiation to cure or harden it, a process which is more rapid than evaporation of solvent at moderate temperatures.
• monomers may be acrylate or methacrylate esters, as is disclosed in EP 0540203B, US-A-5,270,368 and in WO 97 31071. In such ink-jet inks it is necessary to use monomers possessing a low viscosity.
• the present invention provides an ink-jet ink which is substantially free of water or volatile organic solvents, including at least one multifunctional (meth)acrylate monomer, at least one ⁇ , ⁇ -unsaturated ether monomer, at least one radical photoinitiator and at least one colouring agent, the ink having a viscosity of less than 100 mPas at 25°C.
• ⁇ , ⁇ -unsaturated ethers as photopolymerisable monomers in radical systems together with one or more multifunctional (meth)acrylate monomers achieves low viscosity inks with good cure speeds suitable for ink-jet printing. These systems also give acceptable end-user properties such as good cure, adhesion and chemical resistance.
• the ink includes, by weight, from 2 to 15 (particularly preferably 5 to 15) parts of multifunctional (meth)acrylate monomer to 1 part of ⁇ , ⁇ -unsaturated ether monomer.
• the multifunctional acrylate monomer is selected from hexanediol diacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, polyethyleneglycol diacrylate, for example, tetraethyleneglycol diacrylate), dipropyleneglycol diacrylate, tri(propylene glycol) triacrylate, neopentylglycol diacrylate, bis(pentaerythritol) hexa-acrylate, and the acrylate esters of ethoxylated or propoxylated glycols and polyols, for example, propoxylated neopentyl glycol diacrylate, ethoxylated trimethylolpropane triacrylate, and mixtures thereof.
• difunctional acrylates with a molecular weight greater than 200.
• Esters of methacrylic acid can be, for example, hexanediol dimethacrylate, trimethylolpropane trimacrylate, triethyleneglycol dimethacrylate, diethyleneglycol dimethacylate, ethyleneglycol dimethacrylate, 1,4-butanediol dimethacrylate.
• the multifunctional (meth)acrylate monomer is present in an amount from 50 to 95% by weight, preferably from 60 to 80% by weight.
• the ink is substantially free from monofunctional (meth)acrylate monomers, although small amounts may be tolerated.
• the monofunctional (meth)acrylate monomers are preferably the esters of acrylic acid, for example octyl acrylate, decyl acrylate, isobornyl acrylate, phenoxyethyl acrylate, tetrahydrofuryl acrylate, 2-(2-ethoxyethoxy) ethylacrylate, and mixtures thereof.
• ⁇ , ⁇ -unsaturated ether monomers must be present in the composition of the present invention.
• ⁇ , ⁇ -unsaturated ether monomers are vinyl ether monomers, such as triethylene glycol divinyl ether, diethylene glycol divinyl ether, 1,4-cyclohexanedimethanol divinyl ether and ethylene glycol monovinyl ether, as well as ethyl- 1 propenyl ether, triethyleneglycol methyl propenyl ether, triethyleneglycol methyl vinyl ether and 2-cyclopenten-l-yl ether. Mixtures of ⁇ , ⁇ -unsaturated ether monomers may be used.
• the proportion of multifunctional ⁇ , ⁇ -unsaturated ether monomer is preferably between 1 and 20% by weight, more preferably between 7 and 15%), provided that the ratio of acrylate monomer to ⁇ , ⁇ -unsaturated ether monomer lies between 5:1 and 15:1.
• Preferably multifunctional, more preferably difunctional and trifunctional ⁇ , ⁇ -unsaturated ether monomers are used.
• the ⁇ , ⁇ -unsaturated ether monomer is present from 1 to 30% by weight, particularly preferably from 7 to 15%, provided that the ratio of (meth)acrylate monomer to ⁇ , ⁇ -unsaturated ether monomer is between 2:1 and 15:1.
• the ⁇ , ⁇ -unsaturated ether monomer is a vinyl ether monomer.
• the vinyl ether is selected from triethylene glycol divinyl ether, diethylene glycol divinyl ether, 1,4-cyclohexanedimethanol divinyl ether, ethylene glycol monovinyl ether and mixtures thereof.
• the composition contains a vinyl ether monomer and a multifunctional acrylate.
• the compositions include a photoinitiator, which, under irradiation by ultraviolet light, initiates the polymerization of the monomers.
• a photoinitiator which, under irradiation by ultraviolet light, initiates the polymerization of the monomers.
• photoinitiators which produce free radicals on irradiation (free radical photoinitiators) such as, for example, benzophenone, 1-hydroxycyclohexyl phenyl ketone, 2-benzyl-2-dimethylamino-(4- morpholinophenyl)butan-l-one, benzil dimethylketal, bis(2,6-dimethylbenzoyl)-2,4,4- trimethylpentylphosphine oxide or mixtures thereof.
• photoinitiators are known and commercially available such as, for example, under the trade names Irgacure, Darocur (from Ciba) and Lucerin (from BASF).
• the photoinitiator is present from 1 to 20% by weight, preferably from 4 to 10% by weight, of the ink.
• the ink-jet ink of the present invention also includes a colouring agent, which may be either dissolved or dispersed in the liquid medium of the ink.
• the colouring agent is a dispersible pigment, of the types known in the art and commercially available such as, for example, under the trade-names Paliotol (available from BASF pic), Cinquasia, Irgalite (both available from Ciba Speciality Chemicals) and Hostaperm (available from Clariant UK).
• the pigment may be of any desired colour such as, for example, Pigment Yellow 13, Pigment Yellow 83, Pigment Red 9, Pigment Red 184, Pigment Blue 15:3, Pigment Green 7, Pigment Violet 19, Pigment Black 7.
• the total proportion of pigment present is preferably from 0.5 to 15% by weight, more preferably from 1 to 5% by weight.
• components of types known in the art may be present in the ink to improve the properties or performance.
• these components may be, for example, surfactants, defoamers, dispersants, synergists for the photoinitiator, stabilisers against deterioration by heat or light, reodorants, flow or slip aids, biocides and identifying tracers.
• the present invention also provides a method of ink-jet printing using the above- described ink.
• the ink of the present invention is preferably cured by ultraviolet irradiation and is suitable for application by ink-jet printing.
• this ink-jet ink unexpectedly exhibits a desirable low viscosity (preferably less than 100 mPas, more preferably less than 50 mPas and most preferably less than 25 mPas at 25°C). Accordingly, it is not usually necessary to use monofunctional (meth)acrylate monomers, which generally decrease cure speed, although they are not precluded.
• the ink may, for example, contain a multifunctional (meth)acrylate and a vinyl ether as well as a lesser amount (e.g. 1- 15% by weight) of monofunctional (meth)acrylate.
• (Meth)acrylate is intended herein to have its standard meaning, i.e. acrylate and/or methacrylate.
• the inks of the invention may be prepared by known methods such as, for example, stirring with a high-speed water-cooled stirrer, or milling on a horizontal bead-mill.
• Example 1 is a magenta UN ink-jet ink
• Examples 2 to 11 are cyan UN ink-jet. These inks use combinations of alternative multifunctional acrylates and methacrylates to demonstrate the advantage conferred by the use of ⁇ , ⁇ -unsaturated ethers.
• Actilane 505 (wetting resin from Akcros ) 1.56 parts
• Solsperse 32000 (dispersant from Avecia ) 1.25 parts
• Byk 307 (defoamer from BYK Chemie) 0.05 parts
• the product was an ink having a viscosity of 22 mPas at 25°C.
• the ink was printed on to self-adhesive vinyl and irradiated by passing at 40 m/min under light from an iron-doped ultra-violet lamp of power 120 W/cm.
• the ink gave a print with good cure, adhesion and chemical resistance.
• Actilane 505 (wetting resin from Akcros ) 0.67 parts
• Solsperse 32000 (dispersant from Avecia ) 0.45 parts
• Rapi-cure DNE-3 (difunctional vinyl ether from ISP Europe) 10 parts
• Lucirin TPO photoinitiator from BASF
• Benzophenone photoinitiator
• the product was an ink having a viscosity of 18.4 mPas at 25°C.
• the ink was printed on to self-adhesive vinyl and exposed by passing at 40 m/min under light from an iron-doped ultraviolet lamp of power 120 W/cm.
• the ink gave a print with good cure, adhesion and chemical resistance.
• Solsperse 32000 (dispersant from Avecia ) 0.40 parts
• Lucirin TPO photoinitiator from BASF
• Sartomer 350 is trimethylolpropane trimethacrylate which is a multifunctional methacrylate.
• the product was an ink having a viscosity of 19.6 mPas at 25°C.
• the ink was printed on to self-adhesive vinyl and exposed by passing at 20 m/min under light from an iron-doped ultraviolet lamp of power 120 W/cm. As in Example 1, the ink gave a print with good cure, adhesion and chemical resistance.
• Solsperse 32000 (dispersant from Avecia ) 0.40 parts
• Lucirin TPO photoinitiator from BASF
• Actilane 421 is propoxylated neopentylglycol diacrylate and Photomer 2017 is hexanedioldimethacrylate providing an acrylate / methacrylate combination
• the product was an ink having a viscosity of 5.7 mPas at 25°C.
• the ink was printed on to self-adhesive vinyl and exposed by passing at 20 m/min under light from an iron- doped ultraviolet lamp of power 120 W/cm. As in Example 1, the ink gave a print with good cure, adhesion and chemical resistance.
• Example 5
• Rapi-cure DVE-3 (difunctional vinyl ether from ISP Europe) 8.0 parts
• Lucirin TPO photoinitiator from BASF
• Benzophenone photoinitiator
• Actilane 421 is propoxylated neopentylglycol diacrylate and Sartomer 339 is phenoxy ethyl acrylate providing a multifunctional / monofunctional acrylate combination.
• the product was an ink having a viscosity of 13.6 mPas at 25°C.
• the ink was printed on to self-adhesive vinyl and exposed by passing at 40 m/min under light from an iron-doped ultraviolet lamp of power 120 W/cm. As in Example 1, the ink gave a print with good cure, adhesion and chemical resistance.
• Examples 6-8 use Actilane 422 which is dipropyleneglycol diacrylate and vary the ⁇ , ⁇ -unsaturated ether.
• Actilane 422 (UV diluent from Ackros) 69.4 parts
• Solsperse 32000 (dispersant from Avecia ) 0.40 parts
• Rapi-cure CHNE difunctional vinyl ether from ISP Europe
• Lucirin TPO photoinitiator from BASF
• Rapi-Cure CHNE is the divinyl ether of 1,4-cyclohexane dimethanol
• the product was an ink having a viscosity of 14.3 mPas at 25°C.
• the ink was printed on to self- adhesive vinyl and exposed by passing at 40 m/min under light from an iron-doped ultraviolet lamp of power 120 W/cm. As in Example 1, the ink gave a print with good cure, adhesion and chemical resistance.
• Actilane 422 (UN diluent from Ackros) 69.4 parts
• Solsperse 32000 (dispersant from Avecia ) 0.40 parts
• Lucirin TPO photoinitiator from BASF
• the product was an ink having a viscosity of 11.3 mPas at 25°C.
• the ink was printed on to self-adhesive vinyl and exposed by passing at 40 m/min under light from an iron-doped ultraviolet lamp of power 120 W/cm.
• the ink gave a print with good cure, adhesion and chemical resistance.
• Actilane 422 (UN diluent from Ackros) 69.4 parts
• Solsperse 32000 (dispersant from Avecia ) 0.40 parts Irgalite Blue (pigment from Ciba) 3.60 parts
• Lucirin TPO photoinitiator from BASF
• Benzophenone photoinitiator
• the product was an ink having a viscosity of 11.3 mPas at 25°C.
• the ink was printed on to self-adhesive vinyl and exposed by passing at 40 m/min under light from an iron-doped ultraviolet lamp of power 120 W/cm.
• the ink gave a print with good cure, adhesion and chemical resistance.
• Actilane 505 (wetting resin from Akcros ) 1.56 parts
• Solsperse 32000 (dispersant from Avecia ) 1.25 parts
• This ink is as Example 1 but with the vinyl ether replaced by additional propoxylated neopentylglycol diacrylate.
• the product was an ink having a viscosity of 46.8 mPas at 25°C. This viscosity is too high for use in a majority of commercially available ink-jet printing heads.
• the ink was coated onto self-adhesive vinyl using a wire wound bar applicator and irradiated by passing at 40 m/min under light from an iron-doped ultra-violet lamp of power 120 W/cm. When the ink was compared with the ink from Example 1 the cured film showed poorer adhesion and chemical resistance. Comparative Example 2
• Solsperse 32000 (dispersant from Avecia) .25 parts Hostaperm E5BO2 (pigment from Hoechst) .60 parts
• Lucirin TPO photoinitiator from BASF
• This ink is as Example 1 but with the vinyl ether replaced by a mono-functional monomer octyl /decyl acrylate.
• the product was an ink having a viscosity of 22 mPas at 25°C. This viscosity is satisfactory for commercially available ink-jet printing heads, but when the ink was coated onto self-adhesive vinyl using a wire wound bar applicator and irradiated by passing at 40 m/min under light from an iron-doped ultra-violet lamp of power 120 W/cm the cured film showed poorer adhesion and chemical resistance, compared with Example 1.

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• Chemical & Material Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Wood Science & Technology (AREA)
• Organic Chemistry (AREA)
• Inks, Pencil-Leads, Or Crayons (AREA)
• Ink Jet Recording Methods And Recording Media Thereof (AREA)
• Ink Jet (AREA)
• Pens And Brushes (AREA)
• Luminescent Compositions (AREA)
• Manufacture Or Reproduction Of Printing Formes (AREA)

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• 2001
  • 2001-01-29 GB GB0102227A patent/GB2371551B/en not_active Expired - Lifetime
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